Computing machine



June 16, 1931. R. H. STROTHER COMPUTING MACHINE 3 sheets-sheet 1 Filed Jan. 2. 1929 INVENTOR ATTORNEY June 16, 1931. R STROTHER 1,810,329

COMPUTING MACHINE Filed Jan. 2, 1929- 3 Sheets-Sheet 2 I & NEW BAL, OLD BAL 60 NEW OLD INVENTOR @Qi; a;

ATTORNEY June 16, 1931. STRQTHER 1,810,329

COMPUTING MACHINE Filed Jan. 2, 1929 3 Sheets-Sheet 5 l/l H2 O 15 ll;

INVENTOR W, diam w QW Z ATTORNEY Patented June 16, 1931 UNITED STATES PATENT OFFICE ROBERT E. STROTHER, 0F STAMFORD, CONNECTICUT, ASSIGNOR TO REMINGTON AG- OOUNTING MACHINE CORPORATION, OF NEW YORK, N. Y., A CORPORATION 01 N EW YORK COMPUTING MACHINE Application filed January 2, 1928. Serial No. 329,767.

My invention relates to computing ma chines and it has for its principal object to provide certain improvements in what has sometimes been called proof of pick-up mechanism. The invention consists in certain features of construction and combinations and arrangements of devices all of which will be fully set forth herein and particularly pointed out in the claims.

One form of proof of pick-up mechanism truck corresponding to that column Poole mounted a symbol computer havin two dials operated by the main master whee and computing a short symbol consisting of two digits made up by alternate additions and subtractions' of the digits of the balance. This symbol was written at the right of the balance. The paper also contained a column for the pick-up of the old balance and in that column position there was mounted on the main truck a second symbol computer having the same mechanism as the first except that its dial had no numerals thereon. When the operator copied or picked up the old balance the mechanism of this computer computed the same symbol as had previously been computed in the other symbol computer; but as the second computer had no numerals on its (lialsshe was compelled to copy the symbol from the paper. In both symbol computers the act of copying the symbol cleared the computer and mechanism was provided whereby if the computer was not cleared the keys of the machine would be locked and the operator thereby notified that an error had been made.

When in the balance column the symbol was copied from the computer the machine would be locked if said symbol was incorrectly copied. In the old balance column the machine would be locked unless both the old balance itself and also its symbol were correctly copied. If the balance was copied wrong the computer would not compute the same symbol as before and when the old symbol was copied from the paper it would not be the same as that in the computer and the copying of it would not clear the computer. The operator would therefore be immediately warned by the locking up of the machine that she had made a mistake in copying the old balance from the paper.

There are marked advantages in having the symbol consist of a. single digit rather than of two or more and it is the principal object of the present invention to provide an improved form of symbol computer that will compute a symbol consisting of only one digit.

One form of my invention is illustrated in the accompanying drawings in which,

Fig. 1 is an enlarged right hand side view of the symbol computer with the right hand side plate removed.

Fig. 2 is a rear elevation of the same with parts broken away.

Fig. 3 is a plan view in section on the line 3-3 of Fig. 1.

Fig. 4 is a diagrammatic view resembling a plan view similar to Fig. 3 but with some of the mechanism removed or broken away and with parts out of their actual positions so as to showdiagrammatically the engagementof the various gears and other devices.

Figs. 5 and 6 are perspective views of certain rocking frames.

Fig. 7 is a fragmentary front elevation of a portion of the machine.

Fig. 8' is a similar view on a smaller scale and showing an illustrative set-up together with a ledger sheet.

Figs. 9 and 10 are perspective views of some of the cooperating mechanism of the machine.

Fig. 11 shows a fragment of a ledger sheet containing an instance of the use of the invention.

The framing of the symbol computer in the form shown in the drawings, in much like that of an ordinary Wahl totalizer and in some respects is identical with lit comprises two side plates 4 and 5 of the same on"- line as those of a "ilfahl totalizer said frame plates being connected by cross bars 6, 7 and 8 and by three cross rods or shafts 10, 11 and 12 which are identical with corresponding parts of the lVahl totalizer. The computer is at tached to the main truck 13 by the usual dovetailed connection and is held in place by the usual hooks 14: fast on a rock shaft 15 and controlled by a spring 16 and fingerpiece 17, one of said hooks having the usual tooth 18 for cooperation with the positioning and locking rack 20. On the shaft 10 there are journaled a series of thirty-toothed gears in the same position as the carrying gears of a lVahl totalizer; but these are plain spur gears. As best shown in Fig. 4 there is at the left of the series a group of gears 19 corresponding to the various denominations of dollars. Spaced from these as usual are two gears 21 and 22 for dimes and units of cents; and spaced one letter space from the gear 22 is a gear 23 for clearing the symbol from the computer. These thirty-tooth gears are all actuated by the main or vertical master wheel 29 of the machine.

Above the rod or shaft 10 is a shaft 24 having its reduced end journaled in the side plates 4 and 5 and having thereon a pinion 25 continuously meshing with the gear 21 and having also pinions 26 meshing with every alternate one of the gears 19. This shaft has also another pinion 27 just to the left of the gear 23.

Forward of the rod 10 a shaft 28 has its reduced ends journaled in the side plates 4 and 5 and carrying fast thereon or integral therewith another series of pinions. Of these, pinion 30 meshes with gear 23, pinion 31 with gear 22 and pinions 32 mesh with alternate ones of the gears 19. The construction is such that the gear 22 is through shaft 28 and its pinions geared to the gears 23 and 22 and, counting leftward, with the odd-numbered gears 19; while gear 21 through shaft 24 is geared to the even-numbered gears 19. Counting the whole system of dollar and cents wheels beginning at the right the odd-numbered wheels all turn together and the evennumbered wheels all turn together; and the wheel 23 turns with the odd-numbered dollar and cents wheels. I

A dial 33 occupies approximately the position of one of the dials of a lVahl totalizer and it can be read through a window 34, Fig.

7, in the casing 39 of the symbol computer,

which casing with that exception is similar to that of an ordinary Wahl totalizer. The dial 33 is fast on a shaft 35 whose reduced ends are journaled in the side plates 4 and 5. This shaft carries a somewhat elongated pinion 36 having eleven teeth. In the computer 1 the dial 33 has on its periphery eleven characters ten of which in the present instance consist of the numerals 0 to 9 inclusive the eleventh position being marked with the latter It shift gear 37 in continuous mesh with the pinion 3(5 and having the ends of its teeth beveled, is carried by a shaft 38 whose reduced ends are journaled in two nipples 19 secured to the frame plates d and 5 and projecting inward from said plates in order to provide a bearing long enough to permit of a longitudinal shifting of the shaft 38 without causing its ends to project outward from said frame plates. This shaft normally occupies the middle position shown in Figs. 3 and 1 in which the shift gear 37 is partially enmeshed both with the thirty-toothed gear wheel 22 and with the pinion 27. When the computer is in gear with the master wheel 29 in one of the odd-nuu-iliered denominational positions and a numeral key is struck the operation of the master dog 10 causes the shaft 38 and gear 37 to slide leftward until said gear is moved into fuller mesh with the wheel 22 and entirely out of mesh with the pinion 27. \Vhen the master wheel turns it operates directly that one of the thirty-toothed gears with which it is in mesh and through the shaft 38 all of the other odd-numbered wheels as well as the symbol wheel 23, the even-numbered wheels being not rotated. In this op eration the master wheel is turned in the direction for addition and the gears 23, 37 and 36 are turned in the directions of the arrows in Fig. 1. The numerals on the dial 33 are so arranged that this has the effect of subtraction.

When the master wheel 29 is in engagement with one of the even-numbered denominational wheels the operation of the master dog 40 causes the shaft 38 and gear 37 to be shifted rightward causing said gear to move out of mesh with the gear 22 and into fuller mesh with the pinion 27. This causes the gear 37 to be driven, not directly from one of the thirty-toothed gears but indirectly through the pinion 27 with the result that the dial 33 is turned in the opposite direction to that indicated by the arrow in Fig. 1. In this operation the even-numbered denominational wheels all turn and the odd-numbered wheels do not.

The result of the writing of a number in the zone defined by the computer 1 is therefore to add on the dial 33 all of the evennumbered digits of that number and to sub tract on said dial all of the odd-numbered digits so that the final position of the dial will be that arrived at by alternately adding and subtracting the digits of the number written. The character that shows through the window 34 at the end of this operation is what I call the symbol of the number. If the carriage be stepped to the position of the wheel 23 and this symbol be copied said symbol will be subtracted from itself and the dial 33 will bebrought to its zero position.

It will be perceived that in case the symbol should be X it will be necessary to turn the wheel ten spaces in order to clear it. One form of the Remington machine, known commercially as the Sterling machine, has a key adapted to turn the master wheel ten teeth and this key is marked in my machine with the letter X and is connected with a type bar to print that letter.

The shaft 38 is controlled in its shifting movements by a slide 41 situated between the shaft 24 and the rod 12. Said slide has a bracket 42 secured thereto by rivets 43 and extending forward, its forward end being slotted to embrace a flange 44 on the shaft 38 so that said slide 41 and said shaft move right and left in unison. bevel-ended alining and locking tooth 45 which normally engages between two teeth of the wheels 21 and 22 as shown in Figs. 1, 3

and 4 thus locking all of the gears in the ma-.

chine against rotation. When this slide and the shaft 38 move leftward the tooth 45 moves out of engagement with the odd-numbered gear 22 thus freeing the odd-numbered gears for rotation, and it moves into fuller engagement with the gear 21 thus retaining all of the even-numbered gears locked. When the slide 41 and shaft 38 move rightward bringing the gear 37 into full mesh with pinion 27 the tooth 45 moves out of engagement with the gear 21 thus releasing the even-numbered gears for rotation and maintaining the oddnumbered gears locked.

The slide 41 is operated and controlled by two pieces 46 and 47 which are pivoted on the frame rod 12 and are themselves operated by the master dog 40'of the machine. The rod 12 passes through holes 48 in the two pieces, Figs. 5 and 6. The piece 47 comprises a longitudinal bar from which three arms 50, 51 and 52 project upward and forward and it is these three arms that are'directl pivoted on the rod 12. A series of lugs or ngers 53 project downward from the cross bar into the path of motion of the master dog 40, there being'one of these fingers in each even-numbered denominational position, so that this bar is rocked clockwise in Fig. 1 whenever a number is written in'one of these positions. The piece 46 has two pivoted arms 54 and 55- and it also comprises a cross bar which extends downward in front of that of piece 47. Projecting downward and rearthe two pieces are assembled on rod 12, the

Said slide has a Y fingers 53 and 57 alternate with each other as shown in Fig. 2.

A pin 58 projects from the end of arm 54 into a cam slot 60 in the slide plate 41. This slot inclines upward and toward the right so that when the piece 46 is rocked the slide 41 and gear 37 will be moved to the left. The arm 51 has a pin 61 projecting therefrom into a cam slot 62 in the slide plate 41 and so shaped that said plate is slid toward the right when the piece 47 is rocked. Each of the cam slots ,60 and 62 is formed with an extension 64 to permit the movement of the slide.

By an inspection of Fig. 4 it will be seen that when the pins 58 and 61 are both in normal position they hold the slide 41 in its middle position.

The ieces 46 and 47 are returned to normal position by any suitable springs 65. Each of said pieces has a pin 66 projecting upward therefrom and normally resting against the rod 11 to limit the motion of the parts so as to prevent the pressure of the springs from being taken by the pins 58 and 61 a which would cause friction of said pins on the slot extensions 64.

The whole construction is such that whenever a key is struck when the master wheel is in engagement with the wheel 22 or 23 or with any odd-numbered wheel '19 the piece 46 will be rocked and will cause the slide 41 and gear 37 to be moved leftward, and whenever a key is struck in an even-numbered denominational position the piece 47 will be rocked and the slide and pinion willbe moved rightward. I

The clearance-testin computer comprises a circular disk 67 on the shaft 35 ofthe dial wheel 33, said disk havin a single'notch 68 in its eriphery, and a toot 70 on a swinging arm 1 rests in said notch when said dial shows the 0 at the sight opening. The arm 71 is fast on a'rock-shaft 72 pivoted at its ends in the frame plates 4 and 5. An arm 73 projecting from said shaft is articulated with, an arm 74 projecting rearward from a rock shaft 75 which'is also pivoted in the frame plates 4 and 5. Said rockshaft has projecting upward from its ends two fingers 76 and 77 which extend through mechanism in the a the cover plate of the computer. These two fingers-occupy the same positions and perform the same functions as similar fingers described in the Poole Patent No. 1,758,172 hereinbefore referred to. A spring 78 actin on arm 74 presses tooth 70 against disk 6 and when said disk is in 0 position moves said tooth into the notch 68 thereby swinging fingers V 76 and 77 to their forward position shown in Fig. 1. When the dial 33 is turned out of its 0 position, the disk 67 forces arm 71 rearward, moving fingers 76 and 77 to their rear positions. H

The RmlIt on accountin machine in Wh1Chth6 Sym 01 computer a ve described this cross truck is mounted the usual cross totalizer 90. The truck 87 has a projecting stop piece 91 adapted to strike the usual stop lever 92 which lever is connected by slide link 93 with a locking device described in the l/Vahl patent above referred to. It is this look that is used in the scheme of the present invention and the showing of the lever 92 and link 93 is intended as a conventional illustration of it. The cross truck 87 is drawn leftward by the usual pick-up beam 94 having the lug or hook 95 adapted to be engaged by a heel on each of the vertical totalizers. 96 is the usual guard bar associated with the pick-up beam.

The machine is equipped with a clearance proof mechanism for the cross totalizer of the sort described in the patent to Poole, #raomcr, dated April 22, 1924.. A finger 97 projecting upward from the cross totalizer 90 can swing front and back and it occupies its forward position when the totalizer is not clear and its rear position when the totalizer clear. A suitably shaped frame plate 98, secured to the end of the main casting 83, has a three armed lever 100, 101, 102 pivoted thereto at 103. A cam bar 104 fastened to the horizontal arm 100 has its left or free end inclined so that in case said lever has been dropped down, the finger 97 will, on the next jump back of the cross truck, run under said bar and restore it to its normal upper position in case and only in case said finger is in its rear position, indicating that the totalizer is clear. The bar 104 carries the usual guard cam 105. The depending arm 101 has-a lug 106 adapted, when the arm 100 is depressed, to move the lever 92 to its locking position. This arm also'carries the usual release key 107. The upwardly projectfng arm 102 of the three arm lever is controlled by the usual latch 99 and spring 109. This latch is a bell crank pivoted to the plate 98. Except for a slight rearrangement, all of this clearance roof mechanism is substantiall; as descril in Poole Patent #1,491,167 and it is identical with that shown in Poole shown in the Poole Patent No. 1,7 58,172, but referred to. I,

' Not only is the clearance proof mechanism for the cross totalizer identical with that shown in the Poole patent No.'1,7 58,17 2, but all of the other controlling mechanism controlled by the symbol computers is also iden tical with that application, my improvement being confined to the construction of the symbol computing mechanism itself.

The controlling devices at the middle of the machine above the main truck are the same as in Poole Patent No. 1,758,172. These are mounted in a frame piece or housing 108 secured to the main casting 83. A pivot rod 110 mounted in said housing has pivoted thereon three nested bails 111, 112 and 113. The innermost one 118 of these bails has its forward arm prolonged rightward and it has pivoted thereto a cam piece 114 controlled by a spring 115 and operated by a lug 1'16 2, 7 and 10) on that one of the symbol computers which occupies the column position of the new balance. The construction is such that just as the units of cents wheel 22 of that symbol computer steps out of engagement with the master wheel, the lug 116 will cam upward the piece 114, but when lug 116 passes said piece travelling rightward. said piece 114 turns on its pivot and the bail 113 is not rocked. Said bail 113 has its rear arm 117 hanging downward so that when piece 114 is pushed upward, arm 117 gives a rightward thrust to a push bar 118 which at its right hand end strikes an adjusting screw 120 in latch lever 99 and releases the three armed lever. On this same step of the carriage the cross truck makes its jump-back and will immediately restore the three armed lever provided the cross totalizer is clear.

Each symbol computer has mounted in its upper part by the usual dovetail method a frame bar 121 having a rearwardly projecting branch which at its rear end carries an upwardly projecting flange 122 which is beveled on both its right and left hand edges. In practice two of these symbol computers are used together as shown in Fig. 7 and Fig. 8. In these figures the left hand one of the two symbol computers is for the new balance and the right hand one for the old balance. The left hand or new balance computer has the lug 116, above described, projecting rearward from the flange 122, but this lug is not employed on the old balance or pick-up computer.

The clearance indicating fingers 76 and 77 of the symbol computers cooperate with the outermost one 111 of the threeflbails on the ivot 110. This ba' has its front arm proonged rightwar and equipped with a V shaped cam piece 123 so situated that it-lies in the path of the fingers 76 and 77 when the latter occupy their rear position indicating the non-clear condition of the symbol computer. When the symbol computer is clear, these fingers pass in front of the piece 123 and do not o rite the latter. By an inspection of F'ig. it will be perceived that if one of the symbol computers is'not clear, it will operate the cam piece 114 justas the coinis adap puter passes into or out of the computin zone in either direction of carriage trave. The symbol computer should be clear at all times before coming into a com uting zone, and it should always be cleared fore leaving the computing zone.

The bail 111 has its rear arm 124 hanging vertical and having pivoted thereto a pus bar 125 which at its right hand end (Fig. 9) is adapted to strike an adj ustin screw 126 in a bell crank latch lever-127 pivoted to the frame plate 98 on the same ivot 119 as the latch 99. This latch lever 12 controls a two armed locking lever 128 which is adapted to be operated by a spring 130. Said lever 128 is pivoted at 103 and its depending arm has a restorin key 131 and a lug 132 which latter ted to operate a branch 133 of the lockin lever 92. The construction is such that i a symbol computer passes into or out of a computing column when in a non-clear position, the machine will be locked.

The symbol is, as above described, ofi-set one letter space from the units of cents column. In order to make the computation and the cross totalizer come in the r1 ht denominations, it is necessary for the pic -up heel in the symbol computer to be located just to the right of the units of cents wheel 22. To this end a special pick-up heel 134 is provided (Fig. 2) the same consisting of a piece of sheet metal secured to the side plate 4 and made with the ofi-set construction shown in the drawing. This piece is conveniently secured in place by suitably reducin the end portions of the rods 11 and 12 an passing said reduced portions through the piece 134.

It follows from the above construction that the cross truck will be released and make its j ump-back before the symbol is written, and if the piece 91 were allowed to strike the lever 92, the machine would be locked. To prevent this the following mechanism is pro vided the same as in the Poole Patent No. 1,758,172, controlled by the cam flange 122 on the symbol computer. This flange runs under and elevates a rounded nose 135 on the rightward extension of the forward arm of the middle bail 112, causing the rear arm 136 of said bail to operate a push bar 137 which at its right hand end is pivoted to a bell crank 138 pivoted at 140 to the frame plate 98. The horizontal arm 141 of thisbell crank is provided with certain adjusting devices 142 and is controlled by a spring 143. At its free end it carries a pin 144 projecting into a slot 145 in a vertically disposed bar 146, the upper end of which is connected with arm 141 by a tension spring 147. The lower end of the bar 146 has a cross bar 148, the right hand end of which bears against the frame plate 84 and the left hand end of which is adapted to act as a stop for the cross truck 87 as shown in Figs. 7 and 9. The bar 148 normally occupies an 'upward position where it is out of the path of the cross truck, but the symbol, said nose runs off of said cam and allows the spring 143 to raise the stop 148 to inoperative position. The slot 145 and spr1ngx147 prevent breakage of the arts in case t e cross truck should chance to in its right hand position when the parts above described were operated.

One set-u of the machine is shown conventionally in Fig. 8. This shows a bank led or sheet 150 in place in the machine and wit columns arranged for deposits, checks, new balance, and old balance. In the new balance column there is a symbol computer A having the numerals on its dial wheel 33 and having the lug 116 thereon. In the old balance column is a symbol com uter B having its dial 33 blank except that t e zero position may be marked in order to enable corrections to be made. The de sit and check columns are occupied by ordinary vertical totalizers C and D. As deposits should be added in the cross totalizer and checks subtracted, totalizer D is and totalizer C is not provided with a subtract cam 151 for cooperation with the usual follower 152. This follower normally occupies an upward position in which: the cross master wheel 153 will turn for addition. When the follower is partially depressed, said cross master wheel will be disconnected, and when it is fully depressed, as by the cam 151, the cross master wheel will subtract.

In the new balance column the balance itself should be subtracted in the cross totalizer and the symbol should not be computed in said cross totalizer. Symbol computer A is therefore equipped with a special cam 154, the part of which that corresponds to wheels 19, 21 and 22 is arranged for subtraction, but the last part 155 of which corresponding to wheel 123 is arranged for disconnect. The old balance should be added in the cross totalizer and its symbol not computed therein, and symbol computer B is accordingl provided with a special cam 156, all of wh1c is arranged for addition except that part 157 which corresponds to the writing of the symbol and which is arranged for disconnect.

The apparatus is capable of use in many situations of which that shown in Figs. 8 and 11 will serve as an illustration. Following the new balance column on the ledger sheet 150 is a column 158 for writing the symbols, and following the old balance column is a column 160 for a like purpose. The entry in the new balance column is the last entry made of any particular day, after which this sheet will be restored to the ledger book where it will remain until some future date when another transaction has to be recorded in this account. This sheet will then be put back into the machine, and the first operation on it is to pick up or copy in the old balance column the balance last recorded in the new balance column. The carriage will then be drawn back to the right and the paper line spaced, and then any deposits made or checks cashed will be written in their appropriate columns and there will thus be computed a new balance which will be recorded in the new balance column. The old balance and the deposits are automatically added in the cross totalizer 90 and the checks and new balance subtracted, so that at the end of the operation on each ledger sheet the cross totalizer will be clear. In a bank the operator has to make hundreds of these entries every day, and one of the sources of error consists in incorrectly copying or picking up the old balance. WVith the present apparatus, each new balance has its symbol written after it in the column 158, and when on some future day, this balance is copied in the old balance column, the same symbol is copied in column 160. If the balance is not correctly copied the operator will be warned of that fact by the locking up of the machine.

If, for example, in Fig. 11, the operator had written in the last column 64573.25, the 37 being inverted, the symbol computed by the computer B would have been 5. The op erator would copy the symbol 8 from the paper, which would not clear computer B, and, at the resulting step of the carriage, finger 76 would act on cam piece 123 and lock the machine.

When the slide 42 is moved one way by one of the pieces 46, 47, the part 64 of one of the angled slots in the slide moves so as to embrace the unoperated pin 58 or 61 and to lock the other piece 46 or 47 against actuation. It, therefore, the slide should ever fail to return to normal position, the master dog on the next key stroke would find the piece 46 or 47 locked, and said master dog and the key would themselves be locked and the operator would be unable to proceed with the work; in other words, if the mechanism fails to act properly, the operator will immediate- 1y be apprised of the fact and cannot go on and make a mistake.

Various changes may be made in the details of construction and arrangement without departing from my invention.

What I claim as new and desire to secure by Letters Patent, is

1. In a computing machine in which the digits of a number are computed one after another and which includes a master dog, a symbol computer having in combination a part to be set in accordance with the symbol of a number, computing gearing for so setting said part, said gearing including a change gear mechanism shiftable to two operative positions, and means operated by said master dog for shifting said mechanism to said two positions alternately.

2. In a computing machine in which the digits of a number are computed one after another and which includes a master dog, a symbol computer having in combination a part to be set in accordance with the symbol of a number, computing gearing for so setting said part, said gearing including a change gear mechanism shiftable to two 0 erative positions, means operated by said master dog for shifting said mechanism to said two positions alternately, and means normally locking said gearing and shiftable by said dog to unlock it.

3. In a computing machine in which the digits of a number are computed one after another, a symbol computer having in combination a part to be set in accordance with the symbol of a number, computing gearing for so setting said part, said gearing including a change gear mechanism having a normal position and two operative positions, and means for shifting said mechanism from said normal position tosaid operative positions alternately.

4. In a computing machine in which the digits of a number are computed one after another, a symbol computer having in combination a part to be set in accordance with the symbol of a number, computing gearing for so setting said part, said gearing including a change gear mechanism shiftable to two operative positions, means for shifting said mechanism to said two positions alternately, and means controlled by said shifting means for normally locking said gearing.

5. In a computing machine in which the digits of a number are computed one after another, a symbol computer having in combination a part to be set in accordance with the symbol of a number, a series of denominational wheels, and means for gearing the oddnumbered denominational wheels and the even-numbered denominational wheels to said part alternatively, said means including means whereby the odd-numbered and even numbered wheels cause said part to turn in opposite directions.

6. In a computing machine in which the digits of a number are computed one after another, a symbol computer having in combination a part to be set in accordance with the symbol of a number, a series of denominational wheels, a shaft geared to the odd-numbered wheels, a shaft geared to the even-numbered wheels, and means for gearing said part to said odd and even-numbered wheels alternately in such wise that the odd-numbered wheels cause said part to turn in one direction and the even-numbered wheels cause said part to turn in the opposite direction.

7. In a computing machine in which the digits of a number are computed one after another, a symbol computer having in comamaze bination a part to be set in accordance with the symbol of a number, a series of denominational wheels, change gearing between said wheels and said art, and a toothed slide connected with sai change, aring and acting in one position of said sli e to lock certain of said denommational wheels and in another position to lock other of said wheels.

8. In a computing machine in which the digits of a number are computed one after another, a symbol computer having in com bination a part to be set in accordance with the symbol of a number, a series of denominational wheels change gearing between said wheels and said part, and a toothed slide connected with said change gearing and havin a normal middle position and two operate positions, said toothed slide acting in its middle position to lock two denominational wheels and in one of its operated positions to release one wheel and in its other operated position to release the other wheel.

9. In a computing machine in which the digits of a number are computed one after another, a symbol computer having in combination a part to be set in accordance with the symbol of a number, a series of denominational wheels geared together in two groups, a change gear including a gear adapted to be slid to one position to gear one of said groups to said part and to another position to gear the other group to said part, a slide controlling said gear and acting normally to lock both groups of denominational Wheels and when operated unlocking one group 10. In a computing machine including a step-by-step carriage, a master wheel and a cupying different denominational positions.

11. In a computing machine including a step-by-step carriage, and a master dog, a symbol computer having in combination gearing, a part to be set by said gearing in accordance with the symbol of a number, and

controlling mechanism including two pieces each having denominational fingers to be operated by said master dog, the fingers of the two pieces being interspersed.

12. In a computing machine, having a master dog, a symbol computer having in combination symbol computing mechanism and shift mechanism, said shift mechanism including two pieces operated alternately by said master dog, a slide, and two pin and slot connections one from each of said pieces to said slide whereby said pieces move said slide in opposite directions.

13. In a computing machine, having a master dog. a symbol computer having in I master dog, a slide having two oppositely disosed angular slots therein; sai two pieces eing spring-restored and each having a pin working in one of said slots whereby said pieces normally hold said slide in a middle position and said pieces when operated moving said slide in opposite directions, and when said slide is moved by one of said pieces an angular slot locks the other piece against actuation.

15. In a computing machine, having a master dog, a symbol computer having in combination symbol computing mechanism and shift mechanism, said shift mechanism including two pieces operated alternately by said master dog, a slide, two pin-and-slot connections one from each of said pieces to said .slide whereby said pieces when operated move said slide in opposite directions and when unoperated hold said slide in a middle position. and said slide having a tooth for locking said computing mechanism.

16. In a computing machine, a symbol computer comprising in combination, a series of denominational wheels, a pinion shaft connecting a set of said wheels together, a second pinion shaft connecting another set of said wheels together, a change gear pinion having two operative positions in one of which it meshes with one of said denominational Wheels and in the other of which it meshes with a pinion on one of said shafts, and a part operated by said change gear and adapted to be set in accordance with the symbol of a number.

17. In a computing machine, a symbol computer comprising in combination, a series of denominational wheels, a pinion shaft connecting a set of said wheels together, a second pinion shaft connecting another set of said wheels together, a change gear pinion having two operative positions in one of which it meshes with one of said denominational wheels and in the other of which it meshes with a pinion on one of said shafts. a part operated by said change gear and adapted to be set in accordance with the symbol of a number, a slide for shifting said change gear, and a lock controlled by said slide normally locking both sets of gears and unlocking one set when said change gear is shifted one way and the other set when said change gear is shifted the other way.

Signed at Stamford, in the county of Fairfivld and State of Connecticut, this 31st day of December, A. D. 1928.

ROBERT H. STROTHER. 

